1. Field of the Invention
The present invention relates to an apparatus for producing special yarn made of a fiber strand in which a number of fibers are randomly arranged along the lengthwise direction thereof, in which special yarn at least one of the yarn structural parameters, e.g., yarn count number or number of twists, changes along the lengthwise direction of the yarn.
2. Description of the Related Art
Japanese Examined Patent Publication (Kokoku) No. 38-15968 discloses an apparatus for producing special yarn in which operation levers of a plurality of continuous speed changing devices, arranged within each transmission system between a back-roller, a front roller, and spindles, are successively connected with a driving shaft of a servo motor. The servo motor is controlled by a signal emitting device which follows a pattern cam, and slubs are produced in the yarn.
In the above apparatus, however, the pattern of the special yarn is set by the pattern cam. It takes many hours to change the pattern. As a result, it is not possible to produce special yarns having several types of patterns within a short time. Further, there are many limitations when preparing a pattern to change the yarn count number. Therefore, it is difficult to produce the special yarn having a luxurious appearance.